I started to bleed 2 weeks ago. The bleeding began in the morning, then stopped, but by night I was bleeding once again.

It has fairly heavy, and I went through a couple of pads over the course of 6 days.

I figured it was my period, but here is the thing. My period is never exact, its always a range of 28 to 34 days after my last period. This happened on the 28th day exactly. Also, I didn't cramp as much as I usually do.

Could it be implantation bleeding? Or am I just over-thinking (as I usually do -.-)

Also,
How long does implantation last and how heavy is it generally?